Finally, a Freeze

You may have heard mention on the air a few times that we'd passed the old record for the latest first freeze of the fall at the Raleigh-Durham airport (in records that began in the 1940s), which had been set on November 17, 1989. Since that date, it's been a waiting game to see how far into the season the new record for "latest first freeze" would stretch.

Now we know! The temperature fell to 31 at the airport this morning, November 28, 2009, with light winds, dry air and clear skies in place, establishing the new mark for that particular piece of local weather trivia, and adding 11 days to the old record.

Of course, it is worth noting that temperatures can vary a good deal across the area, especially when winds are light and skies are clear, so we have already experienced freezing temperatures and areas of frost around some parts of our viewing area earlier this fall, in particular back around October 19th (on that day, RDU missed freezing by two degrees) and again around November 7th, when the low at RDU was 33.

For a little perspective on those dates, the climatological average for the first freeze at RDU is October 28th, with a standard deviation of +/- 9 days, so this would seem to be a fairly extreme year given that the eventual date of the first freeze was more than three standard deviations past the average (note on the attached image that the timing at RDU this year is late even by standards of the immediate NC coast).  As for the other extreme, so far in RDU history, the earliest first freeze was recorded on October 3 back in 1974.